This disclosure relates to evaluating cement behind a casing of a wellbore and, or particularly, to integrating multiple modes of acoustic measurements for cement evaluation.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light.
A wellbore drilled into a geological formation may be targeted to produce oil and/or gas from certain zones of the geological formation. To prevent zones from interacting with one another via the wellbore and to prevent fluids from undesired zones entering the wellbore, the wellbore may be completed by placing a cylindrical casing into the wellbore and cementing the annulus between the casing and the wall of the wellbore. During cementing, cement may be injected into the annulus formed between the cylindrical casing and the geological formation. When the cement properly sets, fluids from one zone of the geological formation may not be able to pass through the wellbore to interact with one another. This desirable condition is referred to as “zonal isolation.” Yet well completions may not go as planned. For example, the cement may not set as planned and/or the quality of the cement may be less than expected. In other cases, the cement may unexpectedly fail to set above a certain depth due to natural fissures in the formation.
A variety of acoustic tools may be used to determine well integrity, including verifying that cement is properly installed. These acoustic tools may use pulsed acoustic waves as they are lowered through the wellbore to obtain acoustic cement evaluation data (e.g., flexural attenuation, acoustic impedance measurements, etc.). Different modes of acoustic measurements may be measured in a range of acoustic frequencies. For example, some acoustic tools may be used to generate and measure sonic waveforms, ultrasonic waveforms, etc. Moreover, different modes of acoustic measurements may be particularly suitable for different conditions of the wellbore having different characteristics of mud, cement, and/or casing. While current techniques and modes of acoustic measurements may be suitable for various wellbore conditions, interpreting or discriminating more detailed cement characteristics may still be challenging.